1. Field of the Invention
The present invention relates to an observation system to display a mask area capable of masking a privacy zone and a method to display the mask area. More particularly, the present invention relates to an observation system that calculates a mask area included in an observation area photographed by an observation camera to mask a privacy zone, and a method thereof.
2. Description of the Related Art
Recently, observation cameras have been installed in buildings or on streets to prevent crime and theft. Images photographed by the observation cameras are displayed on monitors of police stations or building management offices to notify policemen or managers of the present status of the locations at which the observation cameras are installed. As described above, an observation system displays on a certain monitor an image photographed by an observation camera. The observation system includes a controller for controlling operation of the observation camera such that a user may control operation of the observation camera and the monitor.
FIG. 1 is a view of a conventional observation system.
Referring to FIG. 1, the conventional observation system includes an observation camera 10, a monitor 20, and a controller 30.
The observation camera 10 includes a charge coupled device (CCD) for photographing a certain observation area and a driving part (not shown) for driving the lens part 15 to rotate in a horizontal direction by a pan angle of 360°, to rotate in a vertical direction by a tilt angle of 180°, and to zoom.
The monitor 20 converts an image signal corresponding to the observation area photographed by the observation camera 10 into an image signal corresponding to the display scheme of the monitor 20 to display on a camera screen 25.
The controller 30 receives a user's adjustment command for adjusting the observation camera 10 and a user-set command for setting operation of the monitor 20 via various operation keys 31 and a joystick 35. The controller 30 outputs a control signal for controlling the observation camera 10 and the monitor 20 according to the received various commands.
The observation system has advantages in preventing crime and theft, however, it also has disadvantages in that privacy is disturbed, because the observation camera covers all the designated areas, including even a privacy area relating to an individual person. To solve this problem, a function is introduced to the observation system that masks the privacy area among the observation area displayed on the camera screen 25.
FIGS. 2A and 2B are views for explaining a method of displaying a mask area according to a conventional observation system.
Referring to FIG. 2A, a user controls the operation of the observation camera 10 via the controller 30 to locate the privacy zone PZ included in the observation area. When the privacy zone PZ is displayed on the camera screen 25, a user sets a mask area M to mask the privacy zone PZ via the controller 30.
Referring to FIG. 2B, a user operates the controller 30 to place the privacy zone PZ on a center of the camera screen 25 and adjusts a size of the mask area M accordingly. The center point (Pi, Ti) of the mask area M is placed on the center of the camera screen 25, and a user operates the certain operation key 31 and the joystick 35 to adjust the size of the mask area M and to set the mask area M. Position data corresponding to the center point (Pi, Ti) of the mask area M and position data corresponding to four vertexes forming the mask area M are stored.
Then, as a user operates the observation camera 10 via the controller 30, the privacy zone PZ displayed on the camera screen 25 is masked via the preset mask area M according to the operation of the observation camera 10. Therefore, it prevents disturbance of the privacy of the privacy zone PZ.
However, according to the conventional method for setting the mask area M, one cannot minutely set the mask area M because the zoom value is fixed and the proportion of the mask area M is fixed to a 4:3 aspect ratio. Additionally, the number of the mask areas M that can be set on a single camera screen 25 is limited to four or less due to limited storage space. Finally, due to the slow speed of calculating the mask area M, the mask area M cannot be displayed on the camera screen 25 as the observation camera 10 pans and tilts by more than a set speed.
Accordingly, a need exists for an improved mask area for and a method of masking a privacy zone captured by an observation system.